Port 3306 — TCP
Client connections to MySQL and MariaDB databases.
What is port 3306 used for?
Connections to MySQL or MariaDB servers.
Transport protocol
TCP
Security precautions
Use TLS and network filtering. Avoid public database exposure unless explicitly required by a controlled architecture.
Should we open this port in the firewall?
Allow this port only when a required service uses it. Apply least privilege: restrict authorized sources, destinations and interfaces, and log connections where appropriate.
How do I check this port?
Test-NetConnection SERVER -Port 3306On Linux, nc -vz SERVER 3306 checks TCP connectivity only. A successful TCP connection does not validate the application, authentication or TLS configuration.
Port-to-service mappings are common conventions. Applications can use a different configured port; confirm the actual service and transport.